1. Field
Example embodiments relate to a wireless universal serial bus (WUSB). More particularly, example embodiments relate to a system and a method capable of enabling a plurality of hosts to access one device within a WUSB protocol.
2. Description of the Related Art
In a wireless communications network a wireless interface is needed to connect network devices. Wireless interfaces e.g. Infrared Data Association (IrDA) and Bluetooth, have been applied by current wireless devices. Recently, research has been advanced that enables the conventional wired network known as universal serial bus (USB) to be used by wireless networks to connect wireless devices. This new technology is known as a wireless universal serial bus (WUSB).
USB is a type of a serial port. It is a standardized wired interface developed to connect a computer with peripheral devices e.g. mouse, printer, modem and speaker. Because USB may have more advantages than other wired interfaces, it has been widely applied to standard personal computer equipment. Recently, USB ports have been used to transfer data between mobile phones and personal computers as well as digital cameras and personal computers. Data transfer speeds of a serial port may be limited to 100 Kbps; while the USB standard supports a data transfer speed of 12 Mbps. In addition, USB does not require installation of complicated adapters.
USB enables 127 devices to be connected in a chain. In addition, users do not need additional software/hardware settings when connecting peripheral devices to a personal computer. USB also makes it possible to reduce the number of ports because all peripheral devices may be connected via the same port. USB enables a portable computer to be made in a small size by reducing the number of ports required. WUSB may include the advantages of wired USB, by using an arbiter-based wireless network to manage variations in a wireless network. In accordance with current WUSB standards, only an arbiter capable of allotting a channel to a WUSB device may become a WUSB host. Accordingly, only one WUSB host may exist within a single arbiter-based wireless network.
For example, there may be a plurality of personal computers constituting one arbiter-based wireless network. One personal computer acting as an arbiter operates a WUSB host so as to be connected with peripheral devices each supporting WUSB. In this case, if any personal computer wants to operate as a WUSB host, it may constitute an independent arbiter-based wireless network. Because the number of arbiter-based wireless networks capable of being within a given range may be limited, the number of WUSB hosts may be also limited. For example, in an arbiter-based wireless network following the IEEE 802.15.3 standard, the number of communication channels is limited to 4 within a given range (e.g., about 10 m). In addition, the IEEE 802.15.3 standard is limited to one piconet per communication channel. The IEEE standard also limits the maximum number of WUSB groups existing within a given range to four. For these reasons, conventional WUSB standards may present a problem in that a plurality of WUSB hosts may not be supported within a given range.
By use of the Ultra Wide Band (UWB) standard, the above-described WUSB, like a wired USB, supports transfer speeds of about 480 Mpbs within about 2 m and of about 110 Mbps within about 10 m. In addition, WUSB may have an architecture that allows up to 127 WUSB devices to be connected in a point-to-point manner using a spatially centered HUB. A conventional technique for establishing a WUSB network may adopt a start architecture similar to that of wired USB. With the start architecture, a host and a device may be connected in a one-to-one manner. In this case, all communication control may be managed by a host. The start architecture does not create significant problems within a conventional wired USB network, but mobile applications may be connected or disconnected frequently based on the distance from a device or another host. For example, the start architecture may not be flexible enough to establish network connections between devices during circumstances characteristic of mobile applications.
In addition, because WUSB devices may be not made to support a plurality of hosts, it may be difficult to configure a complex start network that may be necessitated within a mobile Personal Area Network (PAN) valuing mobility.